Chironomids as water quality indicators in the River Mignone (Central Italy)

Chironomids of the River Mignone (Central Italy) were studied in order to examine their community structure and their relationship to some common biological indices (Biotic Score, Extended Biotic Index, Indice Biotique de Qualité Générale) utilizing the total macroinvertebrate fauna (chironomids generally at family level) for water quality assessment in rivers.A total of 36 taxa belonging to Tanypodinae (2 taxa), Orthocladiinae (22 taxa) and Chironominae (12 taxa) was collected at seven stations four times during a year. The results support the importance of the chironomid identification in water quality assessment studies in rivers, and demonstrate the usefulness of the factorial correspondence analysis as ordination technique based on both qualitative and quantitative chironomid data to determine environmental quality gradients.The value as bioindicator of some taxa was discussed, and chironomid assemblages were related to biological water quality of the river according to functional feeding groups.This study forms part of a larger Research project supported by MPI and CNR grants and is aimed at the biological water quality assessment of the river and at the analysis of the total macrobenthic community.     

Ciliated protozoa and water quality in the Parma River (Northern Italy): long-term changes in the community structure

Ciliated protozoans from sediments of the River Parma (Northern Italy) were collected from 7 stations, selected according to their hydrological, chemical, and physical characteristics, and to river zonation during autumn 1989. Fiftythree species were observed. A saprobic evaluation of the river was made using the taxocenoses observed, and the results were compared with data collected in 1978, when the River Parma still received untreated sewage. In 1989 the hilly section of the stream was found to be more polluted than in 1978, but in the plain section, the saprobic indices were now slightly lower. The marked change in the ciliate community of the hills was accompanied by an increase in organic load, which caused the disappearance of some typical species and dampened the diversifying effects of other environmental factors, producing comparatively similar community structures in that whole zone.     

Fish Communities of the Lower Fraser River (Canada) and a 21-year Contrast

Fish communities were sampled at 14 sites along the lower 120km of the Fraser River, British Columbia by beach seine four times in 1972–1973 and three times in 1993–1994. Of the 37 species collected, peamouth chub, largescale sucker, starry flounder, and northern squawfish were predominant in either density or biomass. Densities and biomass of most species and all fish combined were higher in 1993–1994. Strong rank correlations of species abundance or biomass indicated that the overall fish community structure was very similar in both periods. At smaller spatial scales (reaches of 2–3 sites) and shorter time scales (by season), less than half the comparisons showed any significant correlation indicating changes in community composition. Largescale sucker, one of the largest contributors to biomass in both periods, showed decreased abundance, i.e., lower density, lower biomass, and large differences in the size-frequency distribution, specifically very low representation of small size classes. Other species, especially small-bodied forms, generally increased in numbers. Despite large changes in the lower Fraser River ecosystem in the past 21 years, the overall fish community has shown remarkably little change over that interval.     

Fish Communities of the Sacramento River Basin: Implications for Conservation of Native Fishes in the Central Valley, California

The associations of resident fish communities with environmental variables and stream condition were evaluated at representative sites within the Sacramento River Basin, California between 1996 and 1998 using multivariate ordination techniques and by calculating six fish community metrics. In addition, the results of the current study were compared with recent studies in the San Joaquin River drainage to provide a wider perspective of the condition of resident fish communities in the Central Valley of California as a whole. Within the Sacramento drainage, species distributions were correlated with elevational and substrate size gradients; however, the elevation of a sampling site was correlated with a suite of water-quality and habitat variables that are indicative of land use effects on physio-chemical stream parameters. Four fish community metrics – percentage of native fish, percentage of intolerant fish, number of tolerant species, and percentage of fish with external anomalies – were responsive to environmental quality. Comparisons between the current study and recent studies in the San Joaquin River drainage suggested that differences in water-management practices may have significant effects on native species fish community structure. Additionally, the results of the current study suggest that index of biotic integrity-type indices can be developed for the Sacramento River Basin and possibly the entire Central Valley, California. The protection of native fish communities in the Central Valley and other arid environments continues to be a conflict between human needs for water resources and the requirements of aquatic ecosystems; preservation of these ecosystems will require innovative management strategies.     

Macrobenthic community structure before, during, and after implementation of the Clean Water Act in the Neches River estuary (Texas)

Community structure of macrobenthos in the industrialized, tidal Neches River was studied 12 years after implementation of phase III of the Clean Water Act (CWA). Result were compared with a 1971–72 study conducted before implementation of the CWA and a 1984–85 study conducted after implementation of phases I & II of the CWA. The permitted BOD waste load decreased 93% between the 1971–72 and 1984–85 studies, then increased 19% between 1984–85 and the current study. A total of 50 taxa were collected during the 1971–72 study, 104 during the 1984–85 study, and 110 during the current study. Numbers of taxa per collection at each station increased by a factor of at least two between the 1971–72 and 1984–85 studies and were significantly different at the 0.0001 level. Numbers of taxa per collection at each station were not significantly different between the 1984–85 and the current study (p=0.286). Minimum collection densities in 1984–85 were higher than maximum densities in 1971–72 and were significantly different at the 0.0001 level. Collection densities were not significantly different between the 1984–85 study and the current study (p=0.374). Shannon's annual and station collection diversity values significantly increased (p=<0.05) between the 1971–72 and 1984–85 studies, but not between the 1984–85 and the current study (p=>0.05). Dendrograms of Sorenson's similarity index between all pairs of stations were more alike between the 1971–72 and the current study than between the 1984–85 and the current study. Evidence of some organic enrichment at the upper stations was indicated by the dominance of Limnodrilus hoffmeisteri and depressed oxygen concentrations. Environmental quality in the river has greatly improved since implementation of the CWA in 1972. Most of the improvments were due to phases I & II of the CWA, with little apparent change since implementation of phase III.     

Spatial and Temporal variations of mangrove fish assemblages in Martinique (French West Indies)

A study of the mangrove fish fauna in a bay of Martinique Island (French West Indies) was carried out at different seasons during two consecutive years. fishes were sampled with specific hoop-nets in the coastal areas at 8 stations.A total of 87 species was collected in the bay. Most individuals were represented by small-size specimens and juveniles. The overall species richness varied according to the stations and the sampling periods. The biomass and number of individuals were variable according to the location but remained stable in time. A factor correspondence analysis and a hierarchical clustering with median links were used to follow the evolution of the stations in space and time. Two types of stations were differentiated: the stations characterized by the mangrove and those under the influence of seagrass beds. A seasonal cycle, opposing the dry periods to the others, was observed.Thus, it seems that the use of the mangrove habitat by the fishes is optimized through a complete reorganization of communities in terms of species composition whereas the overall number and biomass remain stable. This model remains valid even for the most constraining biota of the mangrove ecosystem inhabited by a small number of well adapted species.     

Spatial structure of the caddisfly (Insecta,Trichoptera) communities in a river basin in NW Spain affected by coal mining

The changes in caddisfly community structure and composition in the Sil River basin (NW Spain), associated with a gradient in natural conditions and a succession of alterations induced by human activity (mainly urban wastes and coal mining), were studied. Twenty-nine Trichoptera taxa belonging to 11 families were collected. The community diversity analysis showed important spatial differences from source to mouth. Towns and, above all, coal mines produced an increase in sulphate and chloride concentrations and conductivity, which adversely affected the trichopteran assemblages. A stepwise regression model, which introduced sulphate and chloride as variables, explained the changes in diversity produced in the basin (r=0.837, p< 0.01). The lowest diversity and richness values were recorded in the rivers suffering the greatest impact from coal mining or urban wastes. The heterogeneity values of the communities for the main rivers were clearly different. The greatest community heterogeneity corresponded to the main axis of the basin and was explained by spatial variability in water chemical composition. No relation was detected between structural changes at spatial level and geographical distance, such that pollution processes basically controlled the dynamics of the Trichoptera communities. Partial-CCA using distance from the source as a covariable revealed alkalinity and urban and mining-derived pollution as the main factors influencing caddisfly distribution. However, an ordination of sites in relation to the corresponding vectors did not fully agree with the chemical characteristics of the water. The species composition of the Trichoptera communities, therefore, did not seem to be good indicators of the chemical features of the rivers. The structure of the community (as expressed by richness and the Shannon index) appeared to be the better indicator of pollution.     

Influence of a Trout Farm on Water Quality and Macrozoobenthos Communities of the Receiving Stream (Trešnjica River,Serbia)

Trout farming is constantly increasing and poses a serious threat to water quality of clean highland streams. In the present work, we investigated the influence of the farm with the highest trout production in Serbia on water quality and macrozoobenthos communities of the receiving stream, the Trešnjica River. Our study revealed that changes of water chemistry parameters downstream from the trout farm were moderate and mainly confined to the part of the watercourse closest to the wastewater outlet. Moreover, use of food with 0.8% phosphorus content was sufficient to completely eliminate soluble phosphates from water samples of the Trešnjica River. However, the changes in water chemistry were sufficient to cause significant changes in the macrozoobenthos community. These changes remained statistically significant even 500 m downstream and were lost about 3.5 km from the trout farm wastewater effluent. The trout biomass on the farm is a parameter that adequately defines the magnitude of its impact, above all the intensity of its influence on the zoobenthos community structure. The most informative parameters for estimating that influence were the Baetidae/Ephemeroptera ratio, Margelef's index and the Modified biotic index. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

松花江流域大型底栖动物群落结构与水质评价

【目的】松花江流域是中国最早的工业基地之一,其水生态环境遭到严重破坏,环境保护工作面临巨大挑战。开展松花江流域水质评价及典型生物类群多样性状况调查,可为松花江流域生态系统的保护和修复提供依据。【方法】于2016年7月调查整个松花江流域近岸的大型底栖动物群落组成和测定水质理化指标,开展其水质理化特征评价和生物指数评价,并探讨底栖动物群落分布与水环境因子间的关系。【结果】理化指标评价结果显示,南源松花江水质状况最差,处于中度污染;北源松花江处于轻度污染;梧桐河水质最好,处于良好状态。松花江流域3个河段的底栖动物群落结构存在空间差异性。另外,梧桐河的物种多样性最高,北源松花江次之,南源松花江最低。溶解氧和营养元素K的浓度是驱动底栖动物群落组成发生显著性差异的主要环境因子。生物指数评价结果显示,3个河段水质均处于轻度污染状态。【结论】松花江流域水质处于轻度到中度污染状态。有机污染是松花江流域面临的主要水质环境问题,对松花江流域底栖动物群落结构产生了显著影响。因此,控制有机质的输入是维持松花江流域水生态系统平衡的重要举措之一。     

Temporal and Spatial Distribution of Enterobius vermicularis (Nematoda: Oxyuridae) in the Prehistoric Americas

Investigations of Enterobius sp. infection in prehistory have produced a body of data that can be used to evaluate the geographic distribution of infection through time in the Americas. Regional variations in prevalence are evident. In North America, 119 pinworm positive samples were found in 1,112 samples from 28 sites with a prevalence of 10.7%. Almost all of the positive samples came from agricultural sites. From Brazil, 0 pinworm positive samples were found in 325 samples from 7 sites. For the Andes region, 22 pinworm positive samples were found in 411 samples from 26 sites for a prevalence of 5.3%. Detailed analyses of these data defined several trends. First, preagricultural sites less frequently show evidence of infection compared to agricultural populations. This is especially clear in the data from North America, but is also evident in the data from South America. Second, there is an apparent relationship between the commonality of pinworms in coprolites and the manner of constructing villages. These analyses show that ancient parasitism has substantial value in documenting the range of human behaviors that influence parasitic infections.     

Relationships Between Chemical Characteristics of Sediments and Macrofaunal Communities in the Cabras Lagoon (Western Mediterranean,Italy)

The Cabras lagoon is a large and shallow transitional system which periodically suffers from dystrophic events leading to massive losses of its biological resources. Excessive organic matter (OM) and sulphur compounds in sediments are often claimed to be major environmental co-factors triggering these events. However, still limited information is available on their relationships with benthic macrofaunal communities in coastal lagoons. In order to assess these relationships, we conducted monthly field investigations between 2001 and 2002, at three regularly-spaced stations set between the inlet and the mouth of the Cabras lagoon. Results showed reduced conditions of sediments, worsening during the warm season. This was consistent with very high OM contents, up to >‰20%, with annual means of 14–16%. Organic pollution-tolerant taxa, such as Tubificidae nc, Neanthes succinea and Polydora ciliata, dominated poor macrofaunal communities. Results of multivariate analysis indicated significant differences in both environmental variables and macrofaunal community structure and species composition between stations and through different periods. This study documented for the first time in a coastal lagoon that inorganic reduced sulphur pools (acid volatile sulphide and chromium reduced sulphur) of sediments are leading (‚best-matching’) environmental factors influencing the spatial and temporal distribution of macrofaunal abundance and biomass. We conclude that impoverished macrofaunal communities in the Cabras lagoon may show a slight recovery during winter–spring, but tend to regress to an early stage of faunal succession in late summer. We suggest that the combination of excessive amounts of sedimentary organic matter and high temperatures tends to lead to anoxic conditions especially in relatively deeper and more saline waters. These events may concur to periodic increase of production rates of toxic hydrogen sulphide in sediments, which rapidly diffuses to the water column with deleterious effects both on the benthic and pelagic components of the lagoon ecosystem.     

Spatial and temporal dynamics of the microbial community structure in the rhizosphere of cluster roots of white lupin (Lupinus albus L.)

White lupin was grown in a quartz sand–soil mix with poorly available Ca phosphate. The plants were harvested on days 21, 35 and 51 and DNA was extracted from the non-cluster roots, the young, mature and senescent cluster roots with adhering soil. Bacterial community structure was examined by PCR-DGGE of 16S rDNA, digitisation of the band patterns and multivariate analyses. In all root zones the bacterial community structure changed with plant age. The communities in the rhizosphere of the non-cluster roots were always different from those of the cluster roots. The bacterial communities of the cluster roots were cluster age and plant age dependent. The differences in bacterial community structure between the cluster root age classes were significant on days 35 and day 51 but not on d 21. A separate experiment, in which root exudates and samples for PCR-DGGE were collected simultaneously, showed that both bacterial and eukaryotic (18S rDNA) community structures change with organic acid exudation. While eukaryotic community structure of the cluster roots was correlated with citric acid exudation, bacterial community structure was correlated with cis-acconitic, citric and malic acid exudation.     

Periphyton (Aufwuchs) Communities of Ciliated Protozoa in Salt-Polluted Running Waters of the Weser River Basin — Their Structure and Indicator Value (Including Model Ecosystems)

The ciliates in aufwuchs communities on glass slides exposed to different amounts of salt pollution at several locations in the Weser River system were investigated. The results were compared with those from the study of model ecosystems exposed to salts. A comparison of the ciliate occurrence with a number of physical and chemical parameters showed that it is primarily the amount of salt present that determines which species are dominant. The number of species present decreases in the presence of high salt concentrations and in water flowing at a high velocity. A halobic index was formulated to indicate salt pollution quantitatively but turned out not to be useful due to the euryhaline potency of most of the ciliate species. The saprobic index can be used in rivers polluted with salt only if biological indicator species are present in sufficient number.     

Spatial and seasonal variation of the zooplankton in the coastal zone and main khors of Lake Nasser (Egypt)

A prominent feature of Lake Nasser is the presence of khors (dendritic side extensions). We studied the zooplankton of the larger khors and coastal zone of the main lake in 1996 and 1997, and found an assemblage of rotifers, cladocerans and copepods that was partly tropical, partly temperate, at relatively high biomasses. Spatial differences were weak, but the upstream khors (Toushka and Korosko) were consistently richer than the downstream khors (El-Ramla and Kalabsha), with a rather sudden transition around km 150 at El Madiq. Summer standing crops were higher than those in winter by a factor 2–3. The zooplankton of the littoral of the main channel showed the same spatial pattern as that in the khors, being more abundant in spring (average 82300 ind m^–3) than in autumn (average 72700 ind m^–3). Zooplankton dry weight increased from 4 g m^–2 at khor El-Ramla to 7 g m^–2 at khor Toushka. These rather high values had low variation. The number of species, diversity and evenness all showed a high degree of similarity among the khors and in the littoral of the main lake. The lake fish fauna is poor, lacking a pelagic planktivore. The predominance of medium-sized Copepoda (one calanoid, two cyclopoids) in the zooplankton suggests that fish predation is moderate. This is confirmed by the persistence of two Daphnia species at low abundance, although rather strong variations in time suggest that Cladocera suffer from summer predation by invertebrates (copepods) as well as vertebrates (mostly larval fish). Because the zooplankton is underutilised by higher trophic levels, we suggest to assess the benefits of introducing a pelagic zooplanktivorous fish.     

Effects of flooding on recruitment and abundance of Golden Perch (Macquaria ambigua ambigua) in the lower River Murray

Flooding is often considered a stimulus for production of fish in floodplain rivers. In the southern Murray–Darling Basin (MDB), Australia, however, few native fish species have been shown to use the floodplain for spawning, and recruitment has been positively and negatively associated with flooding. In 2010/11, extensive flooding in the lower River Murray provided an opportunity to investigate the recruitment response of Golden Perch (Macquaria ambigua ambigua) following 10 years of drought and floodplain isolation. Annual variation in Golden Perch abundance and recruitment were investigated in anabranch and main channel habitats at Chowilla in the floodplain geomorphic region of the lower River Murray over a 7‐year period incorporating the flood and 6 years of in‐channel flow. Spatial variation in recruitment in the lower River Murray was also investigated by comparing the age structure of Golden Perch in the swamplands/lakes, gorge and floodplain geomorphic regions. Golden Perch abundance in the Chowilla region increased significantly postflooding compared with drought years. Age structures indicated that increased abundance was due predominantly to fish spawned during the flood (2010/11) and the previous year (2009/10), which was characterised by in‐channel flows. Age structure was similar in the nearby Katarapko Anabranch system indicating a uniform postflood recruitment response in the floodplain geomorphic region. Juvenile Golden Perch from the 2010/11 and 2009/10 cohorts were less apparent in the gorge and swamplands/lakes regions. Golden Perch have flexible life histories and will spawn and recruit in association with in‐channel rises in flow and overbank flows, but significant increases in abundance in the lower River Murray may result from overbank flooding. Contemporary approaches to flow restoration in the MDB emphasise overbank flows and floodplain processes. We suggest, however, that environmental flow management that incorporates floodplain and in‐channel processes, at appropriate spatio‐temporal scales, will result in more robust populations of Golden Perch.     

内蒙古图牧吉大鸨种群动态及时空分布稳定性

大鸨（Otis tarda）是我国I级重点保护野生鸟类,对大鸨重要栖息地种群数量的变化趋势进行研究,将为大鸨及其栖息地的保护提供科学依据。2017年至2020年,对内蒙古图牧吉国家级自然保护区内及周边的大鸨种群数量动态进行了全面调查,共选择33个监测地点,对大鸨的数量、性别和分布地点进行了调查。结果表明,大鸨种群数量从2017年193只增加至2020年253只;大鸨1月的越冬种群数量从2017年67只减少至2019年55只,2020年重新恢复至67只。各月大鸨种群数量呈现较大的变化,数量高峰期分别是5月和10月。12月至次年2月,越冬种群数量50 ~ 70只。雌性大鸨从3月开始监测到,数量高峰值出现在4月和5月,达到50 ~ 70只,不同的年份略有差别;6月之后数量开始下降,至9月开始略有回升,在10月以后,野外基本观察不到雌性个体。在野外易于观察的4月,2017至2020年4年中雌雄比的平均值是1︰2。2017年和2018年,大鸨在马鞍山区域分布较多,数量也较为稳定。然而进入2019年,分布地点减少,这可能与当地人类活动的干扰有关;2020年保护区功能区进行了调整,将2014年调整出保护区范围的马鞍山区域重新划入保护区中,湿地和草地面积均有所增加,大鸨分布地点数量逐渐恢复。针对目前保护区存在的问题,建议采取退耕还草、加强保护空缺管理及禁牧等保护措施对大鸨及其栖息地进行保护。     

黄河三角洲芦苇湿地底栖无脊椎动物与环境因子的关系研究——以石油开采区与淡水补给区为例

分别于2018年5月和8月对黄河三角洲芦苇湿地19(淡水补给区11处,石油开采区8处)处采样点的底栖无脊椎动物和水体理化指标进行调查采样,运用统计方法分析两个区域物种组成、优势种、多样性、群落结构以及与环境因子的关系。结果表明:两季共采集到底栖无脊椎动物54种,主要以水生昆虫、腹足纲和软甲纲为主,淡水补给区和石油开采区各类群组成差异明显。独立样本T检验表明淡水补给区和石油开采区水体理化指标间差异显著(P<0.05)。双因子方差分析显示,昆虫纲和腹足纲密度在两区域差异显著(P<0.05),软甲纲和腹足纲密度在季节上差异明显(P<0.05)。底栖无脊椎动物优势种共10种,淡水补给区指示物种8种,而石油开采区未发现有指示物种。聚类和非参数多维排序(nM DS)显示,底栖无脊椎动物群落结构相似性较低; RDA结果表明:淡水补给区底栖无脊椎动物群落结构主要受Cond,TDS,Sal,pH,Eh,HCO₃^-,SO₄^2-等环境因子的影响。石油开采区底栖无脊椎动物群落结构影响较大的环境因子为HCO...     

Spatial sampling bias and model complexity in stream‐based species distribution models: A case study of Paddlefish (Polyodon spathula) in the Arkansas River basin,USA

Leveraging existing presence records and geospatial datasets, species distribution modeling has been widely applied to informing species conservation and restoration efforts. Maxent is one of the most popular modeling algorithms, yet recent research has demonstrated Maxent models are vulnerable to prediction errors related to spatial sampling bias and model complexity. Despite elevated rates of biodiversity imperilment in stream ecosystems, the application of Maxent models to stream networks has lagged, as has the availability of tools to address potential sources of error and calculate model evaluation metrics when modeling in nonraster environments (such as stream networks). Herein, we use Maxent and customized R code to estimate the potential distribution of paddlefish (Polyodon spathula) at a stream‐segment level within the Arkansas River basin, USA, while accounting for potential spatial sampling bias and model complexity. Filtering the presence data appeared to adequately remove an eastward, large‐river sampling bias that was evident within the unfiltered presence dataset. In particular, our novel riverscape filter provided a repeatable means of obtaining a relatively even coverage of presence data among watersheds and streams of varying sizes. The greatest differences in estimated distributions were observed among models constructed with default versus AIC_C‐selected parameterization. Although all models had similarly high performance and evaluation metrics, the AIC_C‐selected models were more inclusive of westward‐situated and smaller, headwater streams. Overall, our results solidified the importance of accounting for model complexity and spatial sampling bias in SDMs constructed within stream networks and provided a roadmap for future paddlefish restoration efforts in the study area.     

Lobomycosis in Bottlenose Dolphins (<Emphasis Type="Italic">Tursiops truncatus</Emphasis>) from the Indian River Lagoon,Florida: Estimation of Prevalence,Temporal Trends,and Spatial Distribution

Lobomycosis (lacaziosis) is a chronic fungal disease of the skin that affects only dolphins and humans. Previous studies have shown a high prevalence of lobomycosis in bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon, Florida (IRL). We studied the occurrence and distribution of lobomycosis in the IRL using photo-identification survey data collected between 1996 and 2006. Our objectives were to (1) determine the sensitivity and specificity of photo-identification for diagnosis of lobomycosis in free-ranging dolphins; (2) determine the spatial distribution of lobomycosis in the IRL; and (3) assess temporal patterns of occurrence. Photographs from 704 distinctly marked dolphins were reviewed for skin lesions compatible with lobomycosis. The presumptive diagnosis was validated by comparing the results of photographic analysis with physical examination and histologic examination of lesion biopsies in 102 dolphins captured and released during a health assessment and 3 stranded dolphins. Twelve of 16 confirmed cases were identified previously by photography, a sensitivity of 75%. Among 89 dolphins without disease, all 89 were considered negative, a specificity of 100%. The prevalence of lobomycosis estimated from photographic data was 6.8% (48/704). Spatial distribution was determined by dividing the IRL into six segments based on hydrodynamics and geographic features. The prevalence ranged from <1% in the Mosquito Lagoon to 16.9% in the south Indian River. The incidence of the disease did not increase during the study period, indicating that the disease is endemic, rather than emerging. In summary, photo-identification is a useful tool to monitor the course of individual and population health for this enigmatic disease.     

Distribution of the fish rotan (Perccottus glenii Dybowski, 1877) in the Irtysh River basin and analysis of possible consequences for environment and people

Since 1916, rotan (Perccottus glenii Dybowski, 1877) has widely distributed in northwestern Eurasia. In 1973–1976, rotan populations were first detected in the basin of the Irtysh River: in Lake Peschanoe (Mertvoe) of Chelyabinsk oblast in the basin of the Tobol, a tributary of the Irtysh. In 1975, this fish was introduced to one of the ponds of the city of Chelyabinsk. Analysis of the spatiotemporal dynamics of findings shows that earlier records of the fish correlate with the network of roads, and later findings, with the river network. The results of a special inspection of isolated and floodplain water bodies (n = 77) performed within Chelyabinsk, Kurgan, Omsk, and Tyumen oblasts in 2006 indicate that at present this unwanted invader occurs in the major part of the Tobol basin. The northernmost finding of this species is from the floodplain of the Tobol in the vicinity of Tobolsk, from the Karachino oxbow (58°02′N, 68°10′E). Rotan has also been found at the Irtysh headwaters as well as in the basins of its other tributaries: Ishim and Om. The expansion of rotan threatens the floodplain water bodies of the middle Irtysh. This species carries diseases, competes with other fish species for food, and actively eats young fish of these species. Therefore, the data on rotan distribution in the tributaries of the Irtysh should be taken into account when analyzing the dynamics of the fish community of this river. Biology of rotan assumes its influence on the functioning of the natural foci of opisthorchiasis.